Since foam resins, represented by styrene foam or polyethylene foam, have characteristics of heating resistance, light weight or cushion property, they are often used as packing materials (transporting boxs, etc.) of fishery products or fresh foods, wrapping materials for transporting electrical instruments, machines and others. Further, they are previously used in various industrial fields about building materials. Especially, in view of formability, moisture and chemical proofings and for being low in cost and harmless, the polyethylene foam has recently been frequenty used.
Those foam resin products are indeed expedient in use, but turn out burdensome after their services because they are bulky. Besides, as waste resin materials are produced in factories, enterprises or stores, they have difficulties in post treatments. The waste materials of foam resin products have been burnt up so far, but being made of a high molecular compound, firing furnaces are damaged by the high calories necessary for incineration, or much smoke causes problems of circumferential pollution.
Fish or vegetable markets have often installed smelting machines as measures for treating waste resin products, but the smelting machine has been large-scaled to occupy a wide space and has required much kerosene, electric power and three to four specialists, so that treating costs have been high. Since the waste foam resin materials were perfectly molten to be liquid, there arose the problem of offensive oder or harmful gas by local heating or thermal decomposition.
The inventor proposed in Japanese Utility Model Application No. 11523/1990 an apparatus of shrinking volumes of waste resin materials which crushes the waste foam materials, extrudes them and at the same time cuts them into chips with a rotating cutter. However, the waste resin materials are not always separated from other packing materials or wrapping ones, but are very often thrown away together with corrugated card boards, cellulous foreigners such as fabric pieces or metallic foreigners such as nails, screws or staples. In this case, the prior art easily causes difficulties such as cloggings in an extruding range, damaging of cutter edges at outletting of the extruded materials from a nozzle, and each time the operation of the machine must be stopped, so that stable continuous operation is difficult and results in high running costs.